<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>双伪元素</title>
    <style>
        .clearfix::before,
        .clearfix::after {
            content: "";
            display: table;
        }

        .clearfix::after {
            clear: both;
        }

        .clearfix {
            /* IE 6\7专有 */
            *zoom: 1;
        }

        .box {
            width: 700px;
            border: 5px solid red;
            margin: 0 auto;
        }

        .damao {
            float: left;
            width: 200px;
            height: 200px;
            background-color: skyblue;
        }

        .ermao {
            float: left;
            width: 300px;
            height: 300px;
            background-color: pink;
        }

        .footer {
            background-color: rgb(0, 255, 136);
            height: 500px;
        }
    </style>
</head>

<body>
    <div class="box clearfix" >
        <div class="damao">大毛</div>
        <div class="ermao">二毛</div>
        <div class="ermao">二毛</div>
        <div class="ermao">二毛</div>
    </div>
    <div class="footer">

    </div>
</body>

</html>